KR20120131396A - Method of manufacturing Electrochromic layer containing Prussian blue for Electrochromic device and Method of manufacturing Thin film electrode comprising the same - Google Patents

Abstract

PURPOSE: A method for manufacturing an electrochromic layer containing prussian blue for the electrochromic device and a method for manufacturing a thin film electrode comprising the same are provided to improve stability, durability and color contrast ratio of the electrochromic layer. CONSTITUTION: Insoluble prussian blue nano particles are synthesized(S100). The prussian blue nano particles can be solved by increase in surface charges of prussian blue nano particles(S120). Sol coating solution is manufactured by mixing the prussian blue nano particles, binder and polar solvent(S140). The sol coating solution is coated on a flexible substrate(S160). Heat treatment is performed on the flexible substrate(S180). [Reference numerals] (AA) Start; (BB) End; (S100) Prussian blue nano particles are synthesized; (S120) The prussian blue nano particles can be solved by increase in surface charges of prussian blue nano particles; (S140) The sol coating solution is manufactured; (S160) The sol coating solution is coated on a flexible substrate; (S180) Thermal treatment is performed on substrate at low temperature

Description

Method of manufacturing Electrochromic layer containing Prussian blue for Electrochromic device and Method of manufacturing Thin film electrode comprising the same}

The present invention relates to a method for manufacturing an electrochromic layer for a prussian blue-containing electrochromic device and a method for manufacturing a thin film electrode including the same. More specifically, the synthetic prussian blue nanoparticles which are insoluble in a polar solvent may be prepared by using only a binder without a dispersant. By preparing a sol coating solution by mixing and applying it on a substrate on which a transparent electrode layer is formed, a low-temperature heat treatment to produce an electrochromic layer, and the thin film electrode by a roll to roll method comprising the above steps The present invention relates to a method for manufacturing a thin-film electrode for a Prussian blue-containing electrochromic device having a large-area mass production and having excellent color contrast ratio, response speed and durability.

Window film is a term for a film that is installed in a building or a vehicle and has a function of controlling the flow of light such as ultraviolet rays, visible rays, and infrared rays passing through a window.

The window film may adjust the reflectance by coating a reflective material such as a metal thin film or by coating a light absorbing material absorbing visible light or infrared light, and in this case, the reflectance or transmittance may be a reflective material or It is fixed by the amount of absorbing material. Therefore, in addition to the method of replacing the film, it is impossible for the user to adjust the reflectance or transmittance to suit the needs.

As an alternative to the above problem, an active variable transmittance window, which allows the user to arbitrarily adjust the transmittance according to season and time, is commercially available, which is a liquid crystal and suspended particle device that controls the arrangement of molecules by an electric field. particles device (SPD) and the electrochromic device using the electrochromic material that changes the color of the material during the oxidation-reduction reaction by the movement of electrons.

The liquid crystal and the suspended particle device (SPD) electrically control only the scattering of light, so that the color cannot be varied depending on the wavelength. However, in the case of the electrochromic device, the transmittance can be varied according to the color change material and the color can be varied. There is an advantage that can change.

On the other hand, recently increasing high-rise residential or office building tends to configure the majority of the wall surface of the glass window, the glass window is coated with a fixed reflective or transmissive film on the surface of the glass window in order to control the transmittance of sunlight. However, due to the purpose of view of landscape, efficient use of energy according to season or time difference, the use of electrochromic glass windows that can freely control the transmission of natural light is increasing, and interest in this is also increasing. . However, currently commercialized electrochromic glass windows are very expensive due to difficulties in the manufacturing process, domestic products are not available.

The electrochromic glass window is a kind of device in which a first electrochromic material layer, an electrolyte layer, and a second electrochromic material layer are sandwiched between two glass windows coated with a conductive transparent electrode layer. The electrochromic material constituting the electrochromic material layer is classified into reducing and oxidative coloring materials, and the reducing coloring materials are typically WO ₃ , Nb ₂ O ₅ , and MoO _3. Or inorganic metal oxides such as TiO ₂ and organic polymer materials such as polyaniline, polypyrrole or polythiophene. Examples of the oxidatively colored materials include prussian blue. And Prussian blue analogues in which a metal is substituted for the Prussian blue, IrO ₂ or NiO.

The Prussian blue has a chemical formula of Fe ₄ ^III [Fe ^II (CN) ₆ ] ₃ , and has a dark blue color. When the combined iron is reduced, Fe ₄ ^II [Fe ^II (CN) ₆ ] ₃ becomes colorless and transparent. Has characteristics. In order to deposit the Prussian blue on a substrate in a thin film form, an electrochemical deposition method is generally performed. Among them, a solution of potassium ferricyanide (K ₃ Fe (CN) ₆ ) and iron chloride () (FeCl ₃ ) is used. To reduce the ferricyanide ions ([Fe (CN) ₆ ] ^3- ) to ferrocyanide ions ([Fe (CN) ₆ ] ^4- ) by flowing a constant reduction current between the working electrode and the counter electrode to be deposited. Techniques for simultaneously depositing on the surface of an electrode in combination with iron () ions are disclosed in US Pat. Nos. 4,449,39,4818352 and 5215821.

However, the electrochemical deposition method requires a complicated electrochemical device in the process, and since it is possible to deposit only a predetermined area of the substrate supported on the electrolyte solution, continuous deposition is impossible, and the counter electrode according to the area of the working electrode to be deposited There was also a constraint that the size of was changed at the same time. In addition, the Prussian blue thin film deposited by the above method has a low crystallinity and a low density, which causes a problem of deterioration in durability due to an oxidation-reduction cycle.

In addition to the electrochemical method, the Prussian blue pigment is mixed with a polymer binder to disperse a solvent to prepare a sol coating liquid having an appropriate viscosity, and the solution may be prepared by various coating methods such as bar coating, spin coating, dip coating, and spray coating. After coating on a substrate, there is a wet coating method in which a solvent is removed to form a thin film. In the case of the thin film manufactured by the above method, the pigment should be uniformly dispersed in nano size in order to ensure transparency so that haze is not observed, and it is easy to move ions due to oxidation-reduction using a sufficient porous polymer binder. shall.

In this regard, in Korean Patent No. 10-0740324, insoluble Prussian blue is dispersed in an organic solvent with an organic polymer dispersant and a pigment, a polymer binder is mixed to prepare a coating solution, and then various wet coating methods are used therein. As a result, a technique of forming a Prussian blue thin film on a conductive transparent substrate is disclosed.

However, the coating solution of the above method is to mix the acrylic dispersant in a significant ratio in order to ensure that insoluble Prussian blue is uniformly dispersed in the solvent, thereby reducing the content ratio of Prussian blue per thickness of the entire thin film relatively. . Therefore, in order to maintain an appropriate color contrast ratio during decolorization, the thickness of the thin film should be formed thick. As described above, the thickness of the thin film has a problem in that decolorization time increases. In addition, due to the organic polymer dispersant there is a problem that the durability is reduced during the oxidation-reduction process.

Accordingly, a first object of the present invention is to synthesize a Prussian blue nanoparticles having a predetermined size in order to deposit a thin film containing the Prussian blue, which is an oxidatively colored material on a flexible substrate, and the Prussian blue nanoparticles. Is prepared by mixing only alkoxysilane-based binders having excellent stability and ion conductivity, and coating a flexible substrate with the sol coating solution and then performing low temperature heat treatment to ensure transparency and have excellent redox cycle durability. The present invention provides a method of manufacturing an electrochromic layer for a color changing device.

In addition, the second object of the present invention is to manufacture a thin film electrode including the step of manufacturing the electrochromic layer by a roll to roll (roll to roll) method to enable large-scale mass production, excellent color contrast ratio, response speed and It is to provide a manufacturing method of a thin-film electrode for prussian blue-containing electrochromic device having durability.

The present invention for achieving the above first object, the step of synthesizing insoluble Prussian blue nanoparticles, increasing the surface charge of the synthesized insoluble Prussian blue nanoparticles to impart solubility in a polar solvent, the Preparing a sol coating solution by mixing soluble Prussian blue nanoparticles with a binder and a polar solvent, applying the sol coating solution on a flexible substrate having a transparent electrode layer, and heat-treating the flexible substrate coated with the sol coating solution. Characterized in that it comprises a step.

In addition, the present invention for achieving the second object includes the steps of providing a flexible substrate, forming a transparent electrode layer on the flexible substrate and forming an electrochromic layer on the transparent electrode layer, The electrochromic layer is formed using a sol coating liquid containing Prussian blue nanoparticles.

Electrochromic layer manufacturing method for a Prussian blue-containing electrochromic device according to the present invention is simply and easily by using a dispersant when preparing a sol coating liquid for forming an electrochromic layer, high color contrast ratio, electrochromic device excellent in stability and durability There is an effect that can be produced for the electrochromic layer.

In addition, the method of manufacturing a thin film electrode including the electrochromic layer has an effect of manufacturing a thin film electrode for an electrochromic device having a uniform large area in a short time by performing a roll-to-roll type continuous process.

1 is a schematic cross-sectional view of a thin film electrode for an electrochromic device including prussian blue nanoparticles according to an exemplary embodiment of the present invention.
2A is a process flowchart illustrating a method of manufacturing an electrochromic layer for a prussian blue-containing electrochromic device according to an exemplary embodiment of the present invention.
2B is a process flowchart illustrating a method of manufacturing an electrochromic layer for a Prussian blue-containing electrochromic device according to another exemplary embodiment of the present invention.
FIG. 3 is a diagram illustrating XRD patterns of Prussian blue nanoparticles and commercially available Prussian blue nanoparticles synthesized at respective synthesis temperatures through Example 1. FIG.
4A is a TEM image of Prussian blue nanoparticles synthesized at a temperature of zero through Example 1. FIG.
4B is a TEM image of Prussian blue nanoparticles synthesized at a temperature of 25 through Example 1. FIG.
4C is a TEM image of Prussian blue nanoparticles synthesized at a temperature of 50 through Example 1. FIG.
4D is a TEM image of Prussian blue nanoparticles synthesized at a temperature of 80 through Example 1. FIG.
4E is a TEM image of commercially available Prussian blue nanoparticles.
FIG. 5 is a TGA graph of Prussian blue nanoparticles synthesized through Example 1 and commercially available Prussian blue nanoparticles.
FIG. 6 is an SEM image of a Prussian blue-containing thin film prepared through Example 3. FIG.
FIG. 7 is an SEM image of a Prussian blue-containing thin film prepared through a comparative example. FIG.
FIG. 8A is a cyclic voltammogram of a water-soluble electrolyte solution of a thin film electrode for a Prussian blue-containing electrochromic device manufactured through Example 3. FIG.
FIG. 8B is a cyclic voltammogram of a non-aqueous electrolyte solution of a thin film electrode for a Prussian blue-containing electrochromic device manufactured through Example 3. FIG.
FIG. 9A is a cyclic voltammogram of a water-soluble electrolyte solution of a thin film electrode for a Prussian blue-containing electrochromic device manufactured through Example 4. FIG.
FIG. 9B is a cyclic voltammogram of a non-aqueous electrolyte solution of a thin film electrode for a Prussian blue-containing electrochromic device manufactured through Example 4. FIG.
FIG. 10A is a cyclic voltammogram of a water-soluble electrolyte solution of a thin film electrode for a Prussian blue-containing electrochromic device manufactured through a comparative example. FIG.
FIG. 10B is a cyclic voltammogram of a non-aqueous electrolyte solution of a thin film electrode for a Prussian blue-containing electrochromic device manufactured through a comparative example.
FIG. 11 illustrates changes in time of oxidation and reduction currents when switching step potentials are applied to the thin film electrodes for the Prussian blue-containing electrochromic devices manufactured according to Examples 3, 4, and Comparative Examples. It is a graph.
FIG. 12 is a graph illustrating changes in light transmittance at maximum absorption wavelengths according to switching potentials of the thin film electrode for the Prussian blue-containing electrochromic device manufactured through Examples 3, 4 and Comparative Examples.
13 is measured at the maximum absorption wavelength according to the number of cycles of switching potential when switching step potential is applied to the thin film electrode for the Prussian blue-containing electrochromic device manufactured in Example 3, respectively It is a graph showing the change of the maximum value and the minimum value of the transmitted light transmittance.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention.

1 is a schematic cross-sectional view of a thin film electrode for an electrochromic device including prussian blue nanoparticles according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a thin film for a Prussian blue-containing electrochromic device manufactured according to the present invention may include a flexible substrate 100, a transparent electrode layer 200 formed on the flexible substrate 100, and an electrical formed on the transparent electrode layer. The color change layer 300 is included.

The electrode for the electrochromic device having the above structure plays a role of coloring and decolorizing by causing an oxidation-reduction reaction when electricity is applied by forming an electrochromic device together with a counter electrode with an electrolyte solution or a polymer electrolyte therebetween.

The flexible substrate 100 may be any one selected from polyethylenephthalate (PET), polyethylenenaphthalate (PEN), polyethersulfone (PES), and polycarbonate (PC), but is not limited thereto. Any substrate can be used as long as it does not cause deformation and has a low oxygen transmission rate.

In addition, the transparent electrode layer 200 may use an indium tin oxide (ITO) or a fluorine-doped tin oxide (FTO) film having a sheet resistance within a range of 5Ω / □ to 100Ω / □, and as the sheet resistance increases, the electrochromic color becomes larger. Since the speed may be reduced and practicality may be limited, the sheet resistance is preferably as low as possible.

The electrochromic layer 300 is formed using a sol coating solution in which Prussian blue nanoparticles, which are oxidatively colored materials, are uniformly mixed. At this time, it is preferable that the sol coating liquid contains 2 to 10 parts by weight of the Prussian blue nanoparticles and 5 to 10 parts by weight of the binder.

The binder may be an organic binder, an inorganic binder, or an organic-inorganic hybrid binder, but by using an alkoxysilane-based binder, which is a kind of an organic-inorganic hybrid binder, a thin film having excellent redox circulation durability may be manufactured. At this time, the alkoxysilane-based binder uses a silane compound as a precursor, and the silane compound is tetramethoxysilane, tetraethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxy It may be at least one selected from silane, phenyltrimethoxysilane, difetylimemethoxysilane and decyltrimethoxysilane.

Figure 2a is a flow chart illustrating a method for producing an electrochromic layer for a Prussian blue-containing electrochromic device according to the present invention.

Referring to Figure 2a, the electrochromic layer for Prussian blue-containing electrochromic device according to the present invention, the step of synthesizing insoluble Prussian blue (PB) nanoparticles (S100), the synthesized insoluble Prussian blue (PB) Increasing the surface charge of the nanoparticles to impart solubility in a polar solvent (S120), and preparing a sol coating solution by mixing the solubility-provided Prussian blue (PB) nanoparticles with a binder and a polar solvent (S140). ), The step of applying the sol coating solution on a flexible substrate having a transparent electrode layer (S160) and the step of heat-treating the flexible substrate on which the sol coating liquid is applied (S180).

First, a substance is precipitated by adding a second reagent containing iron ions (Fe ³⁺ ) to the first reagent containing the ferrocyanide ions ([Fe (CN) ₆ ] ^4- ) that are kept at a constant temperature and stirred After filtration, through the washing process several times to synthesize the Prussian blue (PB) nanoparticles (S100).

At this time, the first reagent may be used potassium ferrocyanide (K ₄ Fe (CN) ₆ ), sodium ferrocyanide (Na ₄ Fe (CN) ₆ ) or ammonium ferrocyanide (NH ₄ Fe (CN) ₆ ) The second reagent may be iron chloride (FeCl ₃ ), iron perchlorate (Fe (ClO 4) ₃ ) or iron nitrate (Fe (NO ₃ ) ₃ ).

The Prussian blue (PB) nanoparticles preferably have a size of 10nm to 30nm. If the particle size is less than 10nm or more than 30nm, the dispersibility is lowered and it is difficult to form a uniform thin film. In addition, in the process of synthesizing the Prussian blue (PB) nanoparticles, a first reagent containing ferrocyanide ions ([Fe (CN) ₆ ] ^4- ) and a second reagent containing iron ions (Fe ³⁺ ) are prepared. When precipitated by mixing in a molar ratio of 0.3mol: 0.4mol, the size can be controlled by adjusting the temperature.

Thereafter, in order to impart solubility in the polar solvent to the insoluble synthetic Prussian blue (PB) nanoparticles, 10 to 15 parts by weight of the surface complexing agent and the polar solvent were added per 100 parts by weight of the nanoparticles, followed by ultrasonic dispersion and stirring in an aqueous solution. After removing the solvent and dried to prepare a soluble synthetic Prussian blue (PB) nanoparticles (S120).

The surface complexing agent is the Prussian blue using potassium ferrocyanide (K ₄ Fe (CN) ₆ ), sodium ferrocyanide (Na ₄ Fe (CN) ₆ ) or ammonium ferrocyanide (NH ₄ Fe (CN) ₆ ) The surface of the (PB) particles can be modified to have a negative charge, or by using iron chloride (FeCl ₃ ), iron perchlorate (Fe (ClO 4) ₃ ) or iron nitrate (Fe (NO ₃ ) ₃ ). The surface of the Prussian blue (PB) particles can be modified to carry a (+) charge. Through this, the agglomeration of particles with respect to the polar solvent can be prevented.

In this case, when the amount of the surface complexing agent added is less than 10 parts by weight, the solubility is lowered. When the amount of the surface complexing agent is more than 15 parts by weight, the redox property of the Prussian blue (PB) nanoparticles is lowered due to the excess surface complexing agent. . Through the above process, the surface charge of the insoluble Prussian blue (PB) nanoparticles may be increased to generate soluble Prussian blue (PB) nanoparticles. In addition, since the insoluble in the polar solvent is used to convert to soluble, there is an advantage that does not require a separate dispersant.

Thereafter, the soluble Prussian blue nanoparticles are mixed with a binder and a polar solvent to prepare a sol coating solution (S140). In order to prepare the sol coating solution, the synthesized soluble Prussian blue nanoparticles are added to a polar solvent, stirred and evenly dissolved, and then 5 to 15 parts by weight of a binder is added to prepare a homogeneous mixed solution.

0.003 to 0.02 parts by weight of 1M HCl inorganic acid is added to the homogeneous mixed solution, stirred for several hours, and hydrolyzed to prepare a sol coating solution. In this case, the hydrolysis time is preferably 10 hours to 20 hours, and if less than 10 hours, the porous silicon oxide is shortly formed so that the coating is not uniformly applied or the adhesion decreases, and the viscosity of the coating liquid is greater than 20 hours. There is a disadvantage that excessively increased coating is impossible.

The ratio of the solvent to the binder and the Prussian blue nanoparticles in the sol coating solution affects the thickness of the formed Prussian blue containing thin film. When the thin film was formed from the sol coating solution prepared in a ratio of 100 parts by weight of the binder and 10 parts by weight of the prussian blue nanoparticles, the thickness was about 300 nm. At this time, when the proportion of the solvent increases, the thickness of the thin film decreases. On the contrary, when the proportion of the solvent decreases, the thickness of the thin film increases.

In addition, the higher the content ratio of the Prussian blue nanoparticles to the binder, the higher the color contrast ratio can be obtained in the thin film of the same thickness, but when the content ratio of the Prussian blue nanoparticles is excessively high, the coating properties are reduced, the thin film formation This is difficult.

In this case, the binder may be an organic binder, an inorganic binder and an organic-inorganic hybrid binder, but by using an alkoxysilane-based binder which is a kind of organic-inorganic hybrid binder, a thin film having excellent redox circulation durability may be manufactured. . The alkoxysilane-based binder uses a silane compound as a precursor, and the silane compound may be tetramethoxysilane, tetraethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, At least one selected from phenyltrimethoxysilane, difetylimemethoxysilane, and decyltrimethoxysilane.

Using the above silane compound as a precursor, a silicon oxide sol (SiO ₂ sol) formed by acid hydrolysis in a polar solvent may be synthesized and used at a viscosity in the range of 0.5 cP to 20 cP. In this case, the polar solvent may be a water-soluble inorganic solvent or a water-soluble organic solvent, may be at least one selected from alcohols and nitriles including water, methanol, ethanol, propanol, ethylene glycol, acetonitrile.

The hydrolysis is possible in both acid and base, but in the basic condition, since the Prussian blue nanoparticles are decomposed by the binder, the hydrolysis is preferable in the acid condition.

Thereafter, the sol coating solution prepared through the above process is applied onto the flexible substrate 100 on which the transparent electrode layer 200 is formed (S160). At this time, it is possible to use a roll-to-roll coating method that can be applied to a large area. For example, it can be applied using any one selected from bar-coating, spray-coating, gravure-coating and microgravure-coating.

Thereafter, the flexible substrate 100 to which the sol coating liquid is applied is subjected to low temperature heat treatment (S180). The sol coating solution is applied onto the flexible substrate 100 on which the transparent electrode layer 200 is formed through the above coating process, and after drying the solvent at room temperature, the electrochromic layer 300 is heat-treated at 70 ° C. to 130 ° C. for 1 to 10 minutes. By forming, the thin-film electrode for a prussian blue containing electrochromic element is produced.

Meanwhile, in addition to the above method, the insoluble synthetic prussian blue nanoparticles are dispersed by a surface complexing agent and a polar solvent for several days by ball-milling to prepare a dispersion solution, and then directly mixed with a binder to form a sol coating solution. Can be prepared.

2B is a process flowchart illustrating a method of manufacturing an electrochromic layer for a Prussian blue-containing electrochromic device according to another exemplary embodiment of the present invention.

Referring to FIG. 2B, the electrochromic layer for the Prussian blue-containing electrochromic device synthesizes insoluble Prussian blue (PB) nanoparticles (S200) and surface complexes the synthesized insoluble Prussian blue (PB) nanoparticles. And preparing a dispersion by ball-milling with a polar solvent (S220), mixing the dispersion with a binder to prepare a sol coating solution (S240), and applying the sol coating solution on a flexible substrate having a transparent electrode layer formed thereon. (S260) and the flexible substrate to which the sol coating liquid is applied are manufactured through a heat treatment step (S280).

The description of the steps duplicated with the above-described manufacturing method will be omitted. The insoluble synthetic Prussian blue nanoparticles may be added to a polar solvent together with a surface complexing agent, followed by ball-milling using zirconia beads to disperse for several days to prepare a dispersion. There is (S220). At this time, the surface complexing agent is at least selected from potassium ferrocyanide (K ₄ Fe (CN) ₆ ), sodium ferrocyanide (Na ₄ Fe (CN) ₆ ) and ammonium ferrocyanide (NH ₄ Fe (CN) ₆ ) Or any one selected from iron chloride (FeCl ₃ ), iron perchlorate (Fe (ClO 4) ₃ ) and iron nitrate (Fe (NO ₃ ) ₃ ), and the polar solvent is a water-soluble inorganic solvent or a water-soluble solvent. It may be an organic solvent, and may be at least one selected from water, methanol, ethanol, propanol, ethylene glycol, alcohols including acetonitrile and nitriles.

Fabrication of Thin Film Electrodes for Prussian Blue-containing Electrochromic Devices

Example 1 Synthesis of Insoluble Prussian Blue Nanoparticles

0.3M whose temperature is kept constant and equal volume of 0.4M solution of potassium ferrocyanide stirred iron () solution of the _{(K 4 Fe (CN) 6} 3H 2 O) (FeCl 3? 3H 2 O) to that precipitated by the slow addition After filtering the material, the Prussian blue nanoparticles were synthesized through several washing processes. At this time, synthesis temperature was maintained at 0 degreeC, 25 degreeC, 50 degreeC, and 80 degreeC, respectively. In addition, a commercially available Prussian blue nanoparticle (Double Band Chem PB27) was prepared to compare the characteristics of the synthesized Prussian blue nanoparticles.

FIG. 3 is a diagram illustrating XRD patterns of Prussian blue nanoparticles and commercially available Prussian blue nanoparticles synthesized at respective synthesis temperatures through Example 1. FIG.

Referring to FIG. 3, the size of the Prussian blue nanoparticles calculated from the width of the (200) peak of the XRD pattern increases as the synthesis temperature increases, but is about 23 nm at the highest synthesis temperature of 80 ° C., It can be seen that the commercial Prussian blue nanoparticles have a size of about one third as compared with the size of 66 nm.

4A is a TEM image of Prussian blue nanoparticles synthesized at a temperature of 0 ° C. through Example 1. FIG.

4B is a TEM image of Prussian blue nanoparticles synthesized at a temperature of 25 ° C. through Example 1. FIG.

4C is a TEM image of Prussian blue nanoparticles synthesized at a temperature of 50 ° C. through Example 1. FIG.

4D is a TEM image of Prussian blue nanoparticles synthesized at a temperature of 80 ° C. through Example 1. FIG.

4E is a TEM image of commercially available Prussian blue nanoparticles.

4A and 4E, it can be seen that as the synthesis temperature increases from 0 ° C. to 80 ° C., the size of the Prussian blue nanoparticles increases, and when compared with commercially available Prussian blue nanoparticles, there is a difference in scale. Also, it can be seen that the size of the synthesized Prussian blue nanoparticles at the highest temperature of 80 ℃ is significantly smaller than the commercial Prussian blue nanoparticles.

FIG. 5 is a TGA graph of Prussian blue (PB) nanoparticles synthesized through Example 1 and commercial Prussian blue (commercial PB) nanoparticles.

Referring to FIG. 5, the degree of hydration of the Prussian blue (PB) nanoparticles calculated from the temperature range of 150 ° C. to 350 ° C., which is the second variation of the TGA graph, ranges from 11 to 14, and the lower the synthesis temperature, the more hydrated. It is found that the degree is high and generally low when compared with commercial Prussian blue (commercial PB) nanoparticles.

Table 1 shows a comparison of the values calculated through the above experimental results.

Synthesis temperature (℃) Average particle size (nm) Hydration degree 0 8.9 13.9 25 12.9 13.4 50 17.8 11.5 80 22.7 11.5 Commercial 66.0 14.1

From the above results, it can be seen that the Prussian blue nanoparticles synthesized by one embodiment of the present invention have a significantly smaller particle size and a lower degree of hydration than commercially available Prussian blue nanoparticles.

Example  2: availability Prussian Blue  Synthesis of Nanoparticles

Examples 1 through into the prussian blue nanoparticles 10g synthesis at a temperature of 25 ℃ in water 100g potassium ferrocyanide _{(K 4 Fe (CN) 6} ? 3H 2 O)) followed by the addition of 1.0g, one ultrasonic sigan It was dispersed and stirred for 24 hours. Thereafter, some undissolved Prussian blue nanoparticles were filtered through a filter paper, and the solvent was evaporated in a filtered solution, followed by drying at 70 ° C. for 24 hours in a vacuum dryer to synthesize soluble Prussian blue nanoparticles.

Example  3: Prussian Blue  Preparation of a coating liquid and

Fabrication of thin film electrode for electrochromic device using the same

0.4 g of the soluble Prussian blue nanoparticles synthesized at a temperature of 25 ° C. through Example 2 was dissolved in 10 ml of a water-soluble methanol (H ₂ O: MeOH = 1: 3 v / v) solvent, and tetraethoxysilane (TEOS) After adding 1.35 ml and uniformly mixing, 0.1 ml of 1.0 M HCl was added and stirred at room temperature for 20 hours to prepare a coating solution. The coating solution was coated on a PET substrate coated with ITO (100Ω / □) having an area of 10 × 10 cm ² , and then heat-treated at 130 ° C. for 5 minutes to produce an electrode for electrochromic devices containing prussian blue. Produced. At this time, the thickness of the formed thin film was 140 nm.

6 is an SEM image of the prussian blue-containing thin film prepared through Example 3. FIG.

Referring to FIG. 6, it can be seen that the Prussian blue-containing thin film prepared in Example 3 is porous and uniformly formed.

Example  4: Prussian Blue  Preparation of a coating liquid and

Fabrication of thin film electrode for electrochromic device using the same

Example 1 prussian blue nanoparticles and 0.4g of potassium ferrocyanide synthesis at a temperature of 25 ℃ through _{(K 4 Fe (CN) 6} 3H 2 O?)) Of the aqueous methanol 10ml 0.07g (H ₂ O: MeOH = 1: 2.3 v / v) dissolved in solvent, ball-milled with zirconia beads for 3 days, followed by 1.35 ml of tetraethoxysilane (TEOS) and 0.1 ml of 1.0 M HCl. The coating solution was prepared by adding and ball-milling for 18 hours. The coating solution was coated on a PET substrate coated with ITO (100Ω / □) having an area of 10 × 10 cm ² , and then heat-treated at 130 ° C. for 5 minutes to produce an electrode for electrochromic devices containing prussian blue. Produced. At this time, the thickness of the formed thin film was 110 nm. The manufacturing method can omit the step of synthesizing the soluble Prussian blue nanoparticles through the second embodiment has a simple and easy advantage.

Comparative example : By electrochemical deposition method

Prussian Blue  Preparation of Electrode for Containing Electrochromic Device

Prepare a 0.02M potassium ferricyanide (K ₃ Fe (CN) ₆ ) solution and a 0.02M ferric chloride (FeCl ₃ ) solution, and prepare a 0.1M KCl solution as an electrolyte solution to coat 2 × 1 cm ² . A Prussian blue-containing thin film electrode was manufactured by flowing an oxidation current of 25 µA / cm ² for 600 seconds to a PET / ITO (100Ω / □) electrode and a platinum counter electrode. The formed thin film was 120 nm thick.

FIG. 7 is an SEM image of a Prussian blue-containing thin film prepared through a comparative example. FIG.

Referring to FIG. 7, since the Prussian blue-containing thin film manufactured by the comparative example has a thickness of 120 nm, the thin film is cracked even though it is thinner than 140 nm, which is the thickness of the Prussian blue-containing thin film prepared through Example 3 You can see that there is.

Prussian Blue  Redox Characteristics of Thin Film Electrodes for Containing Electrochromic Devices and

Spectroscopic evaluation

Using the Prussian blue-containing thin film prepared in Examples 3 and 4 using the Prussian blue nanoparticles prepared in Examples 1 and 2 as a working electrode, SCE (Sat'd Calmel Electrode) ) As the reference electrode and platinum (Pt) as the counter electrode, 0.1M KCl aqueous electrolyte solution and 0.1M LiClO ₄ The oxidation-reduction characteristics and the spectroscopic characteristics of oxidation-reduction were compared and analyzed by constructing a spectroelectrochemical cell in a non-aqueous electrolyte solution.

The oxidation-reduction characteristics were measured by cyclic voltammetry at a scanning speed of 10 mV / s, and the spectroscopic characteristics according to the oxidation-reduction were alternated at + 0.8V for 10 seconds and at -0.8V for 10 seconds. The spectral change of the thin film electrode for the Prussian blue-containing electrochromic device was measured by switching the step potential with.

FIG. 8A is a cyclic voltammogram of a water-soluble electrolyte solution of a thin film electrode for a Prussian blue-containing electrochromic device manufactured through Example 3. FIG.

FIG. 8B is a cyclic voltammogram of a non-aqueous electrolyte solution of a thin film electrode for a Prussian blue-containing electrochromic device manufactured through Example 3. FIG.

FIG. 9A is a cyclic voltammogram of a water-soluble electrolyte solution of a thin film electrode for a Prussian blue-containing electrochromic device manufactured through Example 4. FIG.

FIG. 9B is a cyclic voltammogram of a non-aqueous electrolyte solution of a thin film electrode for a Prussian blue-containing electrochromic device manufactured through Example 4. FIG.

FIG. 10A is a cyclic voltammogram of a water-soluble electrolyte solution of a thin film electrode for a Prussian blue-containing electrochromic device manufactured through a comparative example. FIG.

FIG. 10B is a cyclic voltammogram of a non-aqueous electrolyte solution of a thin film electrode for a Prussian blue-containing electrochromic device manufactured through a comparative example.

Referring to FIGS. 8A to 10B, the second and 100th cycles measured in the water-soluble and non-aqueous electrolyte solution of the thin-film electrode for the Prussian blue-containing electrochromic device manufactured through Examples 3, 4 and Comparative Examples The graph appears. As shown in Figs. 8A to 8B and 9A to 9B, there is no significant difference in the second and the 100th cycle graphs, so that both of Example 3 and Example 4 have very stable reversibility up to 100 cycles. You can see that it is showing.

On the contrary, as shown in FIGS. 10A to 10B, the thin-film electrode for the Prussian blue-containing electrochromic device manufactured by Comparative Example showed a reduction rate of about 80% in 10 times in the aqueous electrolyte solution, and the water-insoluble electrolyte. The solution showed a reduction of about 90% or more in 100 cycles.

Therefore, the Prussian blue-containing thin film electrode manufactured by the conventional electrochemical deposition method is almost impossible to use in the water-soluble electrolyte, and even in the aqueous solution of the non-aqueous electrolyte, the durability is very low, whereas the Prussian produced in accordance with the present invention In the case of the blue-containing thin film electrode, it can be seen that it has very excellent durability without distinguishing between a water-soluble and a water-insoluble electrolyte solution.

Manufacturing method


Thin film thickness
(nm)
Transfer charge during oxidation-reduction
(mC / cm ² )
Response time (s) *

Light transmittance (%)
at 690 nm at -0.8V at + 0.8V at -0.8V at + 0.8V Example 3 140 5.6 4.7 3.6 30.7 87.8 Example 4 110 5.3 4.6 3.7 31.7 90.7 Comparative example 120 6.4 5.5 4.8 31.7 96.7

* Response Time: Time to reach 75% of maximum and minimum transmittance

In addition, when comparing the amount of mobile charge according to the initial oxidation-reduction calculated from the cyclic voltage-current graph, compared to Example 3 and Example 4, although Example 3, Example 4 and Comparative Example are all thin films of similar thickness In the case of the example, it can be seen that there is more transfer of charges, which indicates that the change of the light transmittance of these thin films is similar, and the comparative example should consume more energy during color fading and discoloration.

FIG. 11 illustrates changes in time of oxidation and reduction currents when switching step potentials are applied to the thin film electrodes for the Prussian blue-containing electrochromic devices manufactured according to Examples 3, 4, and Comparative Examples. It is a graph.

Referring to FIG. 11, a switching potential of ± 0.8 V (vs SCE) was applied to the thin film electrode for the Prussian blue-containing electrochromic device manufactured by Examples 3 and 4 and Comparative Example for 10 seconds. Examples 3 and 4 It can be seen that the change time of the oxidation and reduction current of the comparative example is about 1.5 times longer than that of the comparative example. Through this, the discoloration rate of the prussian blue-containing electrochromic thin film electrode manufactured by the present invention in a thin film having a similar thickness was compared to that of the prussian blue-containing electrochromic thin film electrode manufactured by the conventional electrochemical deposition method. You can see how fast.

FIG. 12 is a graph illustrating changes in light transmittance at maximum absorption wavelengths according to switching potentials of the thin film electrode for the Prussian blue-containing electrochromic device manufactured through Examples 3, 4 and Comparative Examples.

Referring to FIG. 12, the maximum absorption wavelength is 690 nm, and when the switching potential is applied to the thin film electrodes for the Prussian blue-containing electrochromic devices manufactured according to Examples 3 and 4, the light transmittance change time at the time of desorption and decolorization is It can be seen that it is faster than the prussian blue-containing electrochromic thin film electrode manufactured by the comparative example, and the light transmittance is about 30% when colored and about 90% when decolorized. This is due to the similar thickness.

Through this, the prussian blue-containing electrochromic thin film electrode manufactured according to the present invention is discolored while having similar light transmittance upon coloration and decolorization with the prussian blue-containing electrochromic thin electrode manufactured by a conventional electrochemical deposition method. It can be seen that the time is shorter and the discoloration energy efficiency is higher.

13 is measured at the maximum absorption wavelength according to the number of cycles of switching potential when switching step potential is applied to the thin film electrode for the Prussian blue-containing electrochromic device manufactured in Example 3, respectively It is a graph showing the change of the maximum value and the minimum value of the transmitted light transmittance.

Referring to FIG. 13, the maximum absorption wavelength is 690 nm, and it is confirmed that the light transmittance change is very small even after 30,000 colored and bleached conversions are performed. Therefore, it can be seen that the thin film electrode for prussian blue-containing electrochromic device manufactured according to the present invention has excellent long-term durability.

100: flexible substrate 200: transparent electrode layer
300: electrochromic layer

Claims (23)

Synthesizing insoluble prussian blue nanoparticles;
Increasing the surface charge of the synthesized insoluble Prussian blue nanoparticle to impart solubility in a polar solvent;
Preparing a sol coating solution by mixing the soluble Prussian blue nanoparticles with a binder and a polar solvent;
Applying the sol coating liquid onto a flexible substrate having a transparent electrode layer formed thereon; And
Electrochromic layer manufacturing method comprising the step of heat-treating the flexible substrate coated with the sol coating liquid. Synthesizing insoluble prussian blue nanoparticles;
Preparing a dispersion by ball-milling the synthesized insoluble Prussian blue nanoparticles with a surface complexing agent and a polar solvent;
Mixing the dispersion with a binder to prepare a sol coating solution;
Applying the sol coating liquid onto a flexible substrate having a transparent electrode layer formed thereon; And
Electrochromic layer manufacturing method comprising the step of heat-treating the flexible substrate coated with the sol coating liquid. The method according to claim 1 or 2,
Synthesizing the insoluble Prussian blue nanoparticles, the first reagent containing the ferrocyanide ions ([Fe (CN) ₆ ] ^4- ) and the second reagent containing iron ions (Fe ^{3 +} ) at a predetermined temperature Electrochromic layer manufacturing method characterized in that the precipitate after mixing. The method of claim 3,
The first reagent is electrochromic, characterized in that potassium ferrocyanide (K ₄ Fe (CN) ₆ ), sodium ferrocyanide (Na ₄ Fe (CN) ₆ ) or ammonium ferrocyanide (NH ₄ Fe (CN) ₆ ) Layer manufacturing method. The method of claim 3,
The second reagent is iron chloride (FeCl ₃ ), iron perchlorate (Fe (ClO 4) ₃ ) or iron nitrate (Fe (NO ₃ ) ₃ ) characterized in that the electrochromic layer manufacturing method. The method of claim 3,
The predetermined temperature is controlled in the range of 0 ℃ to 80 ℃, electrochromic layer manufacturing method characterized in that for changing the size of the Prussian blue nanoparticles synthesized through the temperature control. The method according to claim 6,
The synthesized Prussian blue nanoparticles are electrochromic layer manufacturing method characterized in that it has a size of 10nm to 30nm. The method of claim 1,
The step of imparting solubility in the polar solvent, an electrochromic layer manufacturing method characterized in that the insoluble Prussian blue nanoparticles are added to the polar solvent and the surface complexing agent and then dried. 9. The method according to claim 2 or 8,
The surface complexing agent may be at least one selected from potassium ferrocyanide (K ₄ Fe (CN) ₆ ), sodium ferrocyanide (Na ₄ Fe (CN) ₆ ), and ammonium ferrocyanide (NH ₄ Fe (CN) ₆ ). Or at least one selected from iron chloride (FeCl ₃ ), iron perchlorate (Fe (ClO 4) ₃ ), and iron nitrate (Fe (NO ₃ ) ₃ ). The method according to claim 1 or 2,
The polar solvent is a water-soluble inorganic solvent or a water-soluble organic solvent, characterized in that the electrochromic layer production method. 9. The method of claim 8,
The amount of the surface complexing agent added is an electrochromic layer production method, characterized in that 10 to 15 parts by weight per 100 parts by weight of Prussian blue nanoparticles. The method according to claim 1 or 2,
The binder is an alkoxysilane-based binder using a silane compound as a precursor, characterized in that the electrochromic layer production method. The method of claim 12,
The silane compound is tetraethoxysilane, tetramethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, phenyltrimethoxysilane, difetylimethoxysilane and decyl The method for producing an electrochromic layer, characterized in that at least one selected from trimethoxysilane. The method of claim 1,
The sol coating solution is 2 to 10 parts by weight of Prussian blue nanoparticles, 5 to 10 parts by weight of the binder and 80 to 90 parts by weight of a polar solvent, characterized in that the electrochromic layer manufacturing method. The method according to claim 1 or 2,
The step of applying the sol coating solution on a flexible substrate having a transparent electrode layer is electrochromic layer manufacturing method characterized in that the at least one selected from bar coating, spray coating, gravure coating and micro gravure coating. The method according to claim 1 or 2,
The flexible substrate is a method of manufacturing a thin film electrode for an electrochromic device, characterized in that at least one selected from PET (polyethylenephthalate), PEN (polyethylenenaphthalate), PES (polyethersulfone) and PC (polycarbonate). The method according to claim 1 or 2,
The heat treatment of the flexible substrate coated with the sol coating liquid is electrochromic layer manufacturing method, characterized in that performed in a temperature range of 70 ℃ to 130 ℃. Providing a flexible substrate;
Forming a transparent electrode layer on the flexible substrate; And
Forming an electrochromic layer on the transparent electrode layer;
The electrochromic layer is a method of manufacturing a thin film electrode for an electrochromic device formed using a sol coating solution containing Prussian blue nanoparticles. 19. The method of claim 18,
Forming the electrochromic layer,
Synthesizing insoluble prussian blue nanoparticles;
Increasing the surface charge of the synthesized insoluble Prussian blue nanoparticle to impart solubility in a polar solvent;
Preparing a sol coating solution by mixing the soluble Prussian blue nanoparticles with a binder and a polar solvent;
Applying the sol coating liquid onto a flexible substrate having a transparent electrode layer formed thereon; And
The method of manufacturing a thin film electrode for an electrochromic device comprising the step of heat-treating the flexible substrate coated with the sol coating liquid. 19. The method of claim 18,
Forming the electrochromic layer,
Synthesizing insoluble prussian blue nanoparticles;
Preparing a dispersion by ball-milling the synthesized insoluble Prussian blue nanoparticles with a surface complexing agent and a polar solvent;
Mixing the dispersion with a binder to prepare a sol coating solution;
Applying the sol coating liquid onto a flexible substrate having a transparent electrode layer formed thereon; And
Method of manufacturing a thin film electrode for electrochromic layer device comprising the step of heat-treating the flexible substrate coated with the sol coating liquid. 19. The method of claim 18,
The flexible substrate is a method of manufacturing a thin film electrode for an electrochromic device, characterized in that at least one selected from PET (polyethylenephthalate), PEN (polyethylenenaphthalate), PES (polyethersulfone) and PC (polycarbonate). 19. The method of claim 18,
The transparent electrode layer is a method of manufacturing a thin film electrode for electrochromic device, characterized in that ITO or FTO. 19. The method of claim 18,
The electrochromic layer is formed by applying the sol coating solution on the transparent electrode layer, wherein the electrochromic layer is formed by at least one selected from among bar coating, spray coating, gravure coating, and micro gravure coating. Method of manufacturing a thin film electrode for a color change device.

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